Patents by Inventor David J. Rakestraw

David J. Rakestraw has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 6019882
    Abstract: A compact high pressure hydraulic pump having no moving mechanical parts for converting electric potential to hydraulic force. The electrokinetic pump, which can generate hydraulic pressures greater than 2500 psi, can be employed to compress a fluid, either liquid or gas, and manipulate fluid flow. The pump is particularly useful for capillary-base systems. By combining the electrokinetic pump with a housing having chambers separated by a flexible member, fluid flow, including high pressure fluids, is controlled by the application of an electric potential, that can vary with time.
    Type: Grant
    Filed: April 7, 1998
    Date of Patent: February 1, 2000
    Assignee: Sandia Corporation
    Inventors: Phillip H. Paul, David J. Rakestraw
  • Patent number: 6013164
    Abstract: A compact high pressure hydraulic system having no moving parts for converting electric potential to hydraulic force and for manipulating fluids. Electro-osmotic flow is used to provide a valve and means to compress a fluid or gas in a capillary-based system. By electro-osmotically moving an electrolyte between a first position opening communication between a fluid inlet and outlet and a second position closing communication between the fluid inlet and outlet the system can be configured as a valve. The system can also be used to generate forces as large as 2500 psi that can be used to compress a fluid, either a liquid or a gas.
    Type: Grant
    Filed: June 25, 1997
    Date of Patent: January 11, 2000
    Assignee: Sandia Corporation
    Inventors: Phillip H. Paul, David J. Rakestraw
  • Patent number: 5942093
    Abstract: Method and apparatus for controlling precisely the composition and delivery of liquid at sub-.mu.L/min flow rate. One embodiment of such a delivery system is an electro-osmotically driven gradient flow delivery system that generates dynamic gradient flows with sub-.mu.L/min flow rates by merging a plurality of electro-osmotic flows. These flows are delivered by a plurality of delivery arms attached to a mixing connector, where they mix and then flow into a receiving means, preferably a column. Each inlet of the plurality of delivery arms is placed in a corresponding solution reservoir. A plurality of independent programmable high-voltage power supplies is used to apply a voltage program to each of the plurality of solution reservoirs to regulate the electro-osmotic flow in each delivery arm. The electro-osmotic flow rates in the delivery arms are changed with time according to each voltage program to deliver the required gradient profile to the column.
    Type: Grant
    Filed: June 18, 1997
    Date of Patent: August 24, 1999
    Assignee: Sandia Corporation
    Inventors: David J. Rakestraw, Deon S. Anex, Chao Yan, Rajeev Dadoo, Richard N. Zare
  • Patent number: 5675155
    Abstract: A detection system for sequentially and repetitively scanning a plurality of sample volumes and detecting electromagnetic radiation emitting from each of the sample volumes includes a plurality of coplanar side-by-side capillaries each containing a sample volume, an electromagnetic radiation source, a mirror aligned to receive and reflect electromagnetic radiation, a scanner for moving the mirror, and a detector aligned to receive electromagnetic radiation collected from the sample volumes. In operation, the scanner adjusts the mirror position so that the mirror is positioned to receive the electromagnetic radiation from the electromagnetic radiation source and reflect the electromagnetic radiation sequentially and repetitively to the sample volumes. Emitted electromagnetic radiation from the sample volume is collected and directed to a detector where a signal is generated in response to the interaction of the electromagnetic radiation with the sample.
    Type: Grant
    Filed: April 26, 1995
    Date of Patent: October 7, 1997
    Assignee: Beckman Instruments, Inc.
    Inventors: Stephen L. Pentoney, Jr., David J. Rakestraw